Electrochemical batteries are typically made of two or more electrochemical cells electrically linked in series, for higher voltage output; in parallel, for higher current capability; or in series-parallel arrangements. The individual electrochemical cells (anode, cathode and separator) are either separately contained, with a cell electrolyte, in individually sealed containers; or they are separated by compartments but not sealed apart from each other.
Pressure or welded cell electrical interconnectors between separately sealed cells, provide little, if any, problems relating to corrosion and loss of connection integrity resulting from corrosion. These connections are external to the corrosive cell components and accordingly are not subject to degradation. The separately sealed cells are however not desirable because of reduced electrochemical cell capacity resulting from the wasted volume of the separate cell containers and seals. It has therefore been the practice to simply separate cell components of a battery by thin partitions without elaborate sealing of compartments formed by the partitions. An additional advantage of the latter construction is that, without the separate sealed cell containers, cells are capable of being electrically interconnected by means of bare portions, e.g. integral extending tab portions, of the electrode substrates (typically stainless steel foil or grid). These tabs are electrically connected by either pressure contacts or by being welded together and to the external battery terminals to electrically connect the cells and to form the battery. However, despite the resistance of stainless steel (the commonly utilized electrode substrate) to corrosion, the contact areas are subject to enhanced corrosion rates because of increased electrical resistance at these points. In addition, particularly in high energy density organic cells having electrolyte solvents such as propylene carbonate, films of insulative material tend to form on the electrical connectors. These films, particularly at the anode, cause high internal resistance and premature failure of the cells and batteries. Pressure contact connections are particularly susceptible to failure because of film growth and corrosion. The high potential at which the connection sites are kept (particularly in high energy density lithium containing cells) further exacerbates connection failures.